Magnetic properties of iron-cobalt alloy particles for magnetic recording media

Iron-cobalt alloy particles by reduction of their solution with sodium borohydride have been studied. Coercivity is the maximum at 70%Fe-30%Co, where average particle diameter is 250-300 A. Alloy particles tend to be fine and amorphous as cobalt component increases. Superparamagnetic particles, which cause print through, are proved to be more prevalent for average particle diameter under 250 A. Comparison of characteristics between alloy tape and CrO
2
tape has been also studied.